Media cassettes are used in self-service terminals (SSTs), such as automated teller machines (ATMs). ATMs use media cassettes for a variety of different types of media. However, the most common use of an ATM media cassette is for storing currency (in the form of banknotes) in a manner that allows the currency to be removed, one banknote at a time, from the media cassette (referred to as a currency cassette). The currency is typically stored as a horizontal stack within the currency cassette.
To enable the stored banknotes to be removed reliably, the currency cassette includes a pusher plate that urges the horizontal stack towards a picking area.
When the currency cassette is empty (or nearly empty), it can be manually replenished by removing the lid, retracting the pusher plate, and inserting a new horizontal stack of banknotes between the picking area and the pusher plate. In some currency cassettes, the pusher plate must first be lifted so that it disengages from a ratchet rack near the base of the currency cassette prior to being retracted. This is awkward for a replenisher because a force must be applied downwards on the currency cassette, upwards on the pusher plate, and backwards on the pusher plate, all at the same time.
Another problem associated with replenishing some currency cassettes is that there is a risk that the pusher plate will be accidentally released by the replenisher while the replenisher's hand is between the picking area and the pusher plate. This could injure the replenisher's hand or at least cause some discomfort to the replenisher.
A further problem associated with currency cassettes is that a replenisher may insert too many banknotes (referred to as overstuffing). This can cause excessive force on the banknote nearest the picking area, which can result in failed picking (no banknote picked) or multiple picking (more than one banknote picked in a single picking operation). Neither of these is desirable.
Techniques for reducing the possibility of overstuffing are described in US patent application numbers 20100156034 and 20100156035, which involve using a detent to hold the pusher plate in place while the cassette is being loaded.
One problem associated with some currency cassettes that include an overstuffing detent is that if the replenisher only wants to partially fill the cassette, then the pusher plate may have to be disengaged from the overstuffing detent prior to closing the cassette lid. This again gives rise to the possibility that the replenisher's hand may be in the path of the pusher plate.